Dealing with parentheses within variable names

R shouldn't have trouble with names like that

You will need to enclose the names with backquotes, `odd Name (parens)`, when using them
in expressions.  E.g.,

   > d <- data.frame(`P/E`=c(20,25,22), `% Growth`=c(2.4, 2.8, 5.0), `+-`=c(TRUE,TRUE,FALSE), check.names=FALSE)
   > # In the former you could use "P/E"=, but `P/E` works.  check.names=FALSE stops name mangling
   > d

     P/E % Growth    +-
   1  20      2.4  TRUE
   2  25      2.8  TRUE
   3  22      5.0 FALSE

   > # in the next `% Growth` is essential
   > lm(`% Growth` ~ ., data=d)

   
   Call:
   lm(formula = `% Growth` ~ ., data = d)
   
   Coefficients:
   (Intercept)        `P/E`     `+-`TRUE
          3.24         0.08        -2.44

If you find functions in base R that object to those names, I think we'd
like to fix them.

A core R function that fails with odd names is reformulate():

    > reformulate(c("P/E", "% Growth"), response="+-")

    Error in parse(text = termtext) : <text>:1:16: unexpected input
    1: response ~ P/E+% Growth
                     ^

It works you you add the `` inside the "" (for the termlabels, but not needed
for the response argument):

   > reformulate(c("`P/E`", "`% Growth`"), response="+-")

   `+-` ~ `P/E` + `% Growth`

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
Of Duncan Murdoch
Sent: Thursday, February 28, 2013 1:46 PM
To: Jesus Munoz Serrano
Cc: r-help at r-project.org
Subject: Re: [R] Dealing with parentheses within variable names

On 28/02/2013 11:08 AM, Jesus Munoz Serrano wrote:

Dear all

I'm having some problems with a data set that has parenthesis within the variable

names. A example of this kind of variable names is the following:

				fBodyGyroskewness()Z

The case is that R is having a lot of troubles to identify the variable (probably it does

understand it like a function). I've tried (among other things) to remove the parenthesis
from the name using the following command:

				names(dataFrame) <- sub("()","", names(dataFrame))

but It didn't work.  Sorry if it's a silly issue but I would really appreciate if anybody could

help me. Thank you very much.
R shouldn't have trouble with names like that, but a lot of packages
will (e.g. the ones that construct strings and call parse() on them).
If you find functions in base R that object to those names, I think we'd
like to fix them.  If the functions are in contributed packages, your
mileage may vary.

Duncan Murdoch